Laboratory tests of pull-off strength of chosen USPs attached to concrete sleepers

Resilient under sleeper pads (USPs) are vibration isolators used in the ballasted track structure to improve the dynamic performance of the track, reduce vibrations and protect the ballast layer. Being permanently connected with the rail supports (sleepers or turnout bearers), the pads must exhibit a proper value of the pull-off strength, which ensures that they do not separate from the supports while being transported to the construction site or during many years of exploitation. This study focuses on the experimental determination of the pull-off strength of USPs attached to full scale prestressed concrete sleepers. Three variants are tested: two pads equipped with different anchor layers attached to the sleepers in the production plant and one pad glued to the sleeper in the laboratory. Some of the tested USPs are made of recycled styrene-butadiene rubber (SBR). An important part of the work is specification of the requirements for the pull-off strength of USPs, as well as the requirements for sleepers and turnout bearers equipped with resilient pads.